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The maintenance of iPhone startup constant current and current jump faults

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In this video, we mainly explain the fault phenomenon of constant current and current jump

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Faults of constant current or current jump at startup are common,

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but such faults are very difficult to repair

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Let's first look at the take-off current of a normal machine

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Like the 6S series, after we trigger the switch,

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the current will start to jump from about 70mA

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6S to XS max models, after it is turned on,

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the trigger current will start to jump from about 50mA

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The iPhone 11, 12 series, after starting up,

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the current will start to jump from about 80mA

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Constant current fault means that after the mainboard is turned on,

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we trigger the switch, and the current is directly set between 50- 200mA,

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or between 50- 200mA after a jump

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This kind of current is a constant current fault

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Start-up current jump fault introduction

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After the mainboard is powered on, we trigger the switch,

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and the current jumps cyclically between 0 and 300mA

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For example, when the current jumps from 50mA after power on,

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it will jump to 100mA, then jump to 120 or 180mA,

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then return to 0, and then it starts to jump from 50mA,

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jumping back and forth

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But some current jump faults, the current will not return to 0,

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it jumps from 50mA to 100 or 120mA,

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and then back to 50mA, jumping back and forth

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Phenomena like these are current jump faults

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Next, let's observe these two failure phenomena in the physical mainboard

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Let's take a look at the current jump of a good mainboard

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After triggering the switch, the current starts to jump from 50mA,

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and in some machines it can jump to more than 1A

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After jumping to the highest current, the current will fall back

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At this time, the mobile phone is in the state of turning off the screen

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Let's take a look at the fault phenomenon of constant current

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After the switch is triggered, the current is directly set at about 60mA

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Let's take a look at the mainboard of the iPhone XR

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After triggering the switch, the current is directly set at about 70mA

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Let's take a look at the mainboard of the iPhone 12

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After triggering the switch, the current is directly set at around 116mA

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These fault phenomena are all constant current faults

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Let's take a look at the fault phenomenon of current cycle jump

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After the switch is triggered, the current jumps back and forth,

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sometimes returning to 0, sometimes not returning to 0

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Let's take a look at the mainboard of the iPhone 8P

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After triggering the switch, the current starts to jump from 60mA,

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then to 200mA and returns to 0, and then repeats the cycle

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Let's take a look at the mainboard of the iPhone 12,

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the current of this mainboard will also jump in a loop

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The fault phenomena we have seen are all current cycle jump faults

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Ok, that's all for this video